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For the preparation of RuO2 coatings on Ti substrate, the RuO2 was synthesized in acidic aqueous medium by simple one-step low temperature-controlled microwave (MW) irradiation. The physical composition of synthesized solid phase was analysed through particle size distribution (PSD), whereas the coating was investigated for its capacitive response and activity in oxygen evolution reaction (OER). The oxide phase was found highly polydisperse, with overlapped fractions within rather narrow particle size range and clear tendency toward agglomeration. The smallest particles and their best resolved fractions were synthesized at the temperature just above the boiling point of the reaction medium, and quite below the chloride-to-oxide conversion temperature. Consequently, the highest OER activity was registered for RuO2/Ti anodes prepared from this sample, with strong indication of different oxide structure, with respect to the electrodes prepared from samples synthesized at higher temperatures. However, the coatings from high temperature samples have considerably higher capacitance than those synthesized at lower temperatures. These findings can be rather correlated to the MW temperature-dependent oxide structure than to different morphology analysed through PSD.

Porous electrochemical supercapacitive materials, as an important type of new-generation energy storage devices, require a detailed analysis and knowledge of their capacitive performances upon different charging/discharging regimes. The investigation of the responses to dynamic perturbations of typical representatives, noble metal oxides, carbonaceous materials and RuO2-impregnated carbon blacks, by electrochemical impedance spectroscopy (EIS) is presented. This presentation follows a brief description of supercapacitive behavior and origin of pseudocapacitive response of noble metal oxides. For all investigated materials, the electrical charging/discharging equivalent of the EIS response was found to obey the transmission line model envisaged as so-called „resistor/capacitor (RC) ladder“. The ladder features are correlated to material physicochemical properties, its composition and the composition of the electrolyte. Fitting of the EIS data of different supercapacitive materials to appropriate RC ladders enables the in-depth profiling of the capacitance and pore resistance of their porous thin-layers and finally the complete revelation of capacitive energy storage issues. [Projekat Ministarstva nauke Republike Srbije, br. 172060]

The photoelectrochemical properties of a sol-gel prepared titanium oxide coating applied onto a Ti substrate were investigated. The oxide coating was formed from an inorganic sol thermally treated in air at 350°C. The coating consisted of agglomerates of narrow size distribution around 100 nm. The photoelectrochemical characteristics were evaluated by investigating the changes in the open circuit potential, current transients and impedance characteristics of a Ti/TiO2 electrode upon illumination by UV light in H2SO4 solution and in the oxidation of benzyl alcohol. The electrode was found to be active for photoelectrochemical reactions in the investigated solutions.